Shoot System: Inflorescence and Types of Inflorescence: Types of Racemose and Cymose (For CBSE, ICSE, IAS, NET, NRA 2022)

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Inflorescence

The arrangement of flowers on the floral axis (peduncle) is called inflorescence. Inflorescence could be terminal or axillary. The stalk bearing an inflorescence is called peduncle.

Types of Inflorescence

Inflorescence has been classified into two principal types depend upon the type of branching of peduncle and arrangement of flowers: Racemose and Cymose.

  • Racemose inflorescence: main axis is unlimited in growth, branched or unbranched. It never terminates into a flower and bears flowers in acropetal succession.
  • Cymose inflorescence: main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order.

Differences between Racemose and Cymose Inflorescence

Table Showing Differences between Racemose and Cymose Inflorescence
RacemoseCymose
The growth of the inflorescence is indefiniteThe growth of the inflorescence is definite
The main axis does not terminate in a flower and continuous to growThe main axis and its branches terminate in a flower
Flowers occur in acropetal order (oldest flower below and youngest near the apex)Flowers in basipetal order (terminal flower is older)
The floral axis or peduncle is monopodialThe floral axis or peduncle is multipodial or sympodial

Types of Racemose Inflorescence

With main axis elongated

Table Showing Types of Racemose Inflorescence
TypeCharactersExamples
RacemeMain axis, which is elongated, bears stalked flowersBrassica (mustard)
SpikeLike raceme, but flowers are sessile or unstalkedAchyranthes
SpikeletSpike with one or few flowers called florets. Each spikelet has two sterile glumes and one fertile glume-bearing flower called lemmaTriticum (Wheat)
CatkinLike spike but differs from having a long and pendulous axis, bearing unisexual flowersMulberry (Morus alba0
SpadixLike spike with fleshy axis enclosed by one or several large and brightly colored bracts called the spathesBanana, Colocasia

With main axis shortened

Table Showing Types of Racemose Inflorescence
CorymbLower flowers are long stalked, and the upper ones have a short stalk, so they are placed almost at the same levelCandytuft
UmbelFlowers have stalks of equal length and form a cluster from the same pointCoriander

With main axis flattened

Table Showing Types of Racemose Inflorescence
Head or CapitulumFlattened, more or less convex structure, the receptacle, on which the florets are arranged in a centripetal order. The whole inflorescence is surrounded by an involucre and bears only one or two types of flowers: inner disc florets and outer ray floretsSunflower
Image Showing Types of Racemose Inflorescence

Types of Cymose Inflorescence

Table Showing Types of Cymose Inflorescence
TypeCharactersExamples
Monochasial cyme (uniparous)Main axis terminates into a flower and one lateral branch axis develops from its base, which also ends in a flowerCotton
Dichasial cyme (Biparous)Axis terminates in a flower; two flowers arise laterally in each subsequent whorl and each branch ends in a flowerDianthus, jasmine
Multichasial cymeAxis terminates in a flower, more than two flowers arise laterally in each subsequent whorl, each lateral branch ends in a flowerCalotropis
Image Showing Types of Cymose Inflorescence; (A) Monochasia …

Special Types of Inflorescence

  • Hypanthodium: main axis forms a cup-shaped receptacle with a small opening at the top. Flowers are enclosed within the cup in cymose groups. They are unisexual; male flowers are near the ostiole and fertile female flowers at the base of the cup, e. g. fig (Ficus) .
  • Cyathium: single central female flower surrounded by many groups of male flowers. In each group the male flowers are borne in scorpioid manner. The inflorescence is surrounded by are involucre, e. g. Euphorbia, Pedilanthus.
  • Verticillaster: consists of biparous cyme ending in uniparous scorpioid cymes on either side. This arrangement is repeated on subsequent floral nodes to form the Verticillaster, e. g. Ocimum, Coleus.
    Image Showing Special Type of Inflorescence; Cyathium, Verti …

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